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Discussion Starter #1
Hey everyone,

What's the largest rim width together with largest tire width that's been tried successfully in the front without having to roll the fenders in 18's? 19's? What was the offset?

Same question for rears.
 

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Discussion Starter #2
What? No one? Nobody has been able to fit anything over stock size on the Goat without monkeying with the fenders? WOW!!!

I know for sure that the Monaro VXR sports 19in rims (8in width probably though) w/245s (I think with a 35 profile), and I'd be surprized if they booger-up the fenders on those. I just think that putting 245/35s or even 40s on an 8in rim really compromises sidewall support though. May be that's why Pontiac will only offer 235s on the optional 18s . . .

Anyway, come on, someone must've tried something that worked?! :confused
 

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In a couple of days I will let you know how my upgraded wheels goes. Below are the wheel and tire sizes I ordered.

19 X 8.5 (offset +40mm) fronts with 235/35YR19
19 X 9.5 (offset +45mm) rears with 245/35YR 19

Before I ordered these sizes I test fitted a set of my old 93 Corvette rear wheels to see how the 9.5" would look on the back. And even though the offset was +56mm on the Vette rears, they fit. BARELY, but they fit. With the +56mm offset there was only about a 1/4" gap between the tire and the inner wheel well. But that was only do to the wide section (11.1") with of the MT Drag Radials that I have mounted on the wheels. The 245/35 rear only has a section with of 9.8" so that will free of over a half inch on both sides. But with the +45mm the space between the tire and the wheel well shouldn't be a problem (depending on the backspacing). Anyway, I will let you know how things go.

With the lower profile tires I know I'm gonna have to give up a little of the smooth ride. But personally, I'm okay with that. I guess going form a '98 Vette to the '05 Goat, the suspension of the Goat feels a little mushy to me for a sports car. The firmness of the new tires can only enhance the handling of the car. I HOPE!
 

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Those look good, but something with a higher offset would've looked better. They seem to stick out too far from the wheel well.

To answer the first question. This is from elsewhere on the net. A tentative offset and tire size chart for the GTO.

WIDTH..........OFFSET............WIDTH OF TIRE
7.0...............+26/+65.............215/225/235
7.5...............+33/+61.............215/225/235/245
8.0...............+39/+55..............225/235/245
8.5..............+45/+48..............235/245/255
9.0.(MAX).........+48................245/255
REAR ONLY
8.0................+36/+65.............245/255
8.5................+42/+65...............245/255
9.0.................+48/+65...............255/265/275
9.5................+55/+64...............265/275/285

OFFSETS GREATER THAN SHOWN ABOVE WILL RUB ON REAR
FENDER LIP. (25MM FENDER LIP)

With an 18 x 8 wheel you should be drunning 235/40s. This is what they run on the Monaros in Oz, not 245/40s. Overall diameter is going decrease (ie could throw off your speedo a little) but then you are sure they won't rub. You take your chances with 245s, because then it depends on the brand and model of tire, if they wil rub.
 

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djdub said:
Those look good, but something with a higher offset would've looked better. They seem to stick out too far from the wheel well.

To answer the first question. This is from elsewhere on the net. A tentative offset and tire size chart for the GTO.

WIDTH..........OFFSET............WIDTH OF TIRE
7.0...............+26/+65.............215/225/235
7.5...............+33/+61.............215/225/235/245
8.0...............+39/+55..............225/235/245
8.5..............+45/+48..............235/245/255
9.0.(MAX).........+48................245/255
REAR ONLY
8.0................+36/+65.............245/255
8.5................+42/+65...............245/255
9.0.................+48/+65...............255/265/275
9.5................+55/+64...............265/275/285

OFFSETS GREATER THAN SHOWN ABOVE WILL RUB ON REAR
FENDER LIP. (25MM FENDER LIP)

With an 18 x 8 wheel you should be drunning 235/40s. This is what they run on the Monaros in Oz, not 245/40s. Overall diameter is going decrease (ie could throw off your speedo a little) but then you are sure they won't rub. You take your chances with 245s, because then it depends on the brand and model of tire, if they wil rub.
Well the pictures are kinda deceiving. The rear wheels/tires don't stick out much if not at all. The wheels have a backspacing of just 7 inches. So there is less than 2.5 inches from the mounting surface to the front lip. I should have taken some pics of the rear instead of shooting at an angle. Thanks for the info. I will print it and keep it for future references.
 

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AmesGTO said:
They look good. I like them. You are in the same boat as me, don't hit any potholes:)
Yeah the potholes do have me a little nervous. I have to be extra careful because the wheels are closeout models. So a word to the wise... if you get closeout wheels make sure you get extras in case of damage (especially if you're running low profile tires). Don't be like me, more impressed with the price of the wheel than the availabilty of it.
 

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6QTS11OZ said:
Well the pictures are kinda deceiving. The rear wheels/tires don't stick out much if not at all. The wheels have a backspacing of just 7 inches. So there is less than 2.5 inches from the mounting surface to the front lip. I should have taken some pics of the rear instead of shooting at an angle. Thanks for the info. I will print it and keep it for future references.
The rear wheels look OK. It was the front wheels I was referring to.
 

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djdub said:
The rear wheels look OK. It was the front wheels I was referring to.
I've seen fronts sticking out some in person it looks good. Makes the tires look wide and tough. I'm not talking way out, just a touch.

No matter what these are way better than stockers, way better and I actually do like the stock look.
 

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djdub said:
The rear wheels look OK. It was the front wheels I was referring to.
Like I said before the pics are deceiving. The wheels don't stick out at all. As AmesGTO said, the wheels sticking out a little bit (1/4" or so) wouldn't bother me either. And as you said, to each his own. I'm happy with them and that's all that matters.
 

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Discussion Starter #20
djdub said:
Those look good, but something with a higher offset would've looked better. They seem to stick out too far from the wheel well.

To answer the first question. This is from elsewhere on the net. A tentative offset and tire size chart for the GTO.

WIDTH..........OFFSET............WIDTH OF TIRE
7.0...............+26/+65.............215/225/235
7.5...............+33/+61.............215/225/235/245
8.0...............+39/+55..............225/235/245
8.5..............+45/+48..............235/245/255
9.0.(MAX).........+48................245/255
REAR ONLY
8.0................+36/+65.............245/255
8.5................+42/+65...............245/255
9.0.................+48/+65...............255/265/275
9.5................+55/+64...............265/275/285

OFFSETS GREATER THAN SHOWN ABOVE WILL RUB ON REAR
FENDER LIP. (25MM FENDER LIP)

With an 18 x 8 wheel you should be drunning 235/40s. This is what they run on the Monaros in Oz, not 245/40s. Overall diameter is going decrease (ie could throw off your speedo a little) but then you are sure they won't rub. You take your chances with 245s, because then it depends on the brand and model of tire, if they wil rub.
Thanks much for the chart. However, maybe I'm dense tonight, but I'm a little confused. As I read it you basically said that it is logical from the chart that down under they run 235s on 18x8. Why couldn't they run larger 245s? I must be reading it incorrectly, but as I see it, on 8in widths offsets of +39 to +55 should allow 245s to be run (although the chart doesn't mention the wheel diameters), and with a +45mm offset an 8.5in wide rim should allow 255s to be run w/out issues on all 4 corners; where am I going wrong? :confused
 
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